Instrument closure plate



Patented May 17, 1938 V 2,117,615 INSTRUMENT CLOSURE PLATE Anker E.Krogh, Philadelphia, Pa., assignor to The Brown Instrument Company,Philadelphia, Pa., a corporation of Pennsylvania I Application July 11,1936, Serial No. 90,197

l Claims.

The present invention relates to measuring and control instruments ofthe type in which the instrument housing or casing encloses instrumentmechanism including one or more manually actu- 5 ated adjustmentdevices.

The general object of the present invention is to provide an instrumentof the above mentioned type, with an instrument enclosing casing, formedwith an aperture or apertures suitably located for the actuation througheach such aperture, of .a manually actuated. instrument adjustmentdevice within the casing, and to provide the latter with means normallysecured-in position to cover each such aperture or to otherwise preventactuation through the aperture of the corresponding adjusting device,but which may be readily released for actuation of the adjusting devicesthrough the apertures, by releasing means not readily available tounauthorized persons, so as to avoid unauthorized or accidentaladjustments of said devices.

The present invention is adapted for advantageous use with instrumentsof many different forms and used for widely different purposes.-

The invention in its preferred form, is of especial utility, however, inthe case of an instrument enclosed in a casing provided with a normallylocked door which must be unlocked from time to time by some authorizedperson to permit access to the casing interior for record chart or stripreplacements, or other purposes necessarily eifected from time to time.In such case, the means for preventing unauthorized adjustment of theadjustment devices is preferably in the form of a shield or cover plate,which is movably mounted on the casing, and which is automaticallysecured in its aperture closing position by the casing door, when thelatter is closed, and which is readily movable, when the casing doorisopen, as required to ex- 0 pose each adjustment device aperture, sothat the corresponding adjustment device may then be adjusted throughsaid aperture.

The various features of novelty which characterize the present inventionare pointed out 45 with particularity in the claims annexed to andforming a part of this specification. For a better understanding of theinvention, however, and its advantages, reference should be had to theaccompanying drawing and, descriptive matter in 50 which I haveillustrated'and described a preferrcd embodiment of the invention.

Of the drawing:

Fig. 1 is a frontelevation of an instrument; i m 21s a partial elevationtaken at right angles opening A.

Fig. 3 is a front elevation taken similarly to Fig. 1, of a portion ofthe instrument casing, shown in larger scale than in Fig. l, and withthe shield or' cover member adjusted to a different position; and

Fig. 4 is an elevation of the portion of the instrument casing shown inFig. 3, but with the cover member removed.

In the drawing, A represents the body of an instrument casing which isrectangular in outline 10 at the front of the instrument, and isdisplaced 20 forwardly from the frame of the door, to increase thevolume of the casing space, which is rendered accessible when the dooris opened. As shown, the casing body includes a front wall part A, belowthe level of the bottom of the door B, and formed withtwo apertures Athrough each of which a corresponding instrument adjustment devicewithin the casing may be manually actuated. As shown, one of saiddevices comprises a rotatable operating shaft or stem D extending \30into one of the apertures A and formed at its exposed end with a kerffor engagement by a screw driver or like implement by which the stem Dmay be rotated. As shown, the stem or shaft D carries a dial D at theinner side of the wall 35 part A, the angular position of which, andthere- -by the angular adjustment of the stem D, may

be visually observed through an opening A in the wall A. The secondinstrument adjusting device includes a stem or shaft E, similar to thestem D, and similarly extending into the second The stem E carries adial E observ able through a second opening A In accordance with thepresent invention, a shield or cover plate member F is mounted on thecasing wall for movementinto and out of a normal position in which itcovers both of the apertures A, but the member F is so mounted, shaped,and disposed that it can be moved out of said position only when thecasing door 13 is open.

To this end, in the preferred construction illustrated, the member F ispivotally connected to the casing part A'ior turning movement out of itsnormal position in whiclr it covers the apertures A. and comprisesportions which are A extend beneath, and engage, or are in closeproximity to, the lower edge 01' the door 13, when the "justment shaftE.

Advantageously, and as shown, the portions F are in the form of pinstransverse to the body of the member F and bevelled or tapered at theirouter ends, so that when the door 3 is closed, it

will engage one or the other of the projections F, and cam the member Fback into its normal position, if not already in that position. Asshown, the lower portion of the cover memberF is shaped so that when themember is in its normal position, in which it covers both apertures Aboth apertures A are uncovered so that both dials D and E are visible.

To permit of the ready detachment of the cover member F from theinstrument casing, when desirable, the cover member F opening F is ofkeyhole shape and has its narrow slot portion extending upward towardthe casing doorway and receiving the body of the pin G, in the normalcondition of the member. the pin G is too large to pass through thenarrow slot portion of the keyhole opening F, but is small enough topassthrough the larger lower round. portion of thatopening. In consequence,

when the member F is moved relative to casing part A to bring the roundportion of the opening F into register with the pin G, the latter doesnot prevent movement of the member F bodily away from the casing body.

The risk of accidental separation of the cover plate F from theinstrument casing, is minimized, and the member F is guided in itsnormal turning movement, and has those movements suitably limited, by aheaded pin H carried by the casing part A, and having its body portionnormally received in an are shaped slot F formed in the member F at somedistance from the opening F. The slot F" is concentric with the upperend oi! the keyhole opening F. Movement of the member F relative to thecasing part A', in the direction to bring the round portion oi. thekeyhole opening F into register with'the pin G, is prevented by theengagement of the pin H with the concave wall of the slot F except whenthe angular position of the member F is such as to bring its slot F inline with the pin H. The slot F extends from the concave wall of theslot F to the lower edge of the member F. The opening F, 'slot F,andpins G and H are so relatively disposed that when the angularposition of the -member F is such that slot F is inline with the pin Hand the casing door B is open, the member F may be moved relatively tothe casing in the direction of the length or the narrow slot portion ofthe keyhole opening F. On such movement,

. pin H passes through the slot F and out of engagement with the memberF, and the pin G is brought into register with the larger round por- Thehead of slot portion of the keyhole opening F and the pin H is in linewith the slot F only when the member F is in its normal position inwhich it covers both apertures A and the initial .sepa- Y rationmovement of the member F relative to the casing is directly toward thecasing doorway, and is permitted by the door B only when the latter isin its normal open position. The member F may be remounted on the casingby passing the pin G through the round portion of the keyhole opening,and then moving the member F relative to the casing as required formovement of the pin H through the slot F into the slot F As has alreadybeen indicated, and as will be apparent to those skilled in the art, theinvention is adapted for use with any instrument comprising anadjustment device within an instrument casing, which is desirably madeaccessible for adjustment through an aperture in the easing wall, andwhere it is desirable to prevent unauthorized or accidental adjustmentof the adjustment device. Merely by way of example, it is noted that theparticular instrument illustrated in the drawing, comprises aself-balancing potentiometer measuring mechanism including a pencarriage I automatically adjusted, transversely of a record strip J, inaccordance 'withthe varying values of a thermocouple voltage or otherquantity measured, and that the adjustments of the carriage I relativeto a stationary control table K give corresponding adjustments to theflapper valve of an air actuated control mechanism located in theinstrument casing, back of the wall part A. In the particular instrumentreferred to, the self-balancing potentiometer measuring mechanism is ofthe commercial type employed in the well known and extensively usedBrown potentiometer, made and sold by my assignee, The Brown InstrumentCompany, and the air actuated control mechanism is of the commercialtype employed in the Air-O-Line controller, made and sold by myassignee. One form of the last mentioned mechanism and its operativeconnection to a potentiometer mechanism of the above mentionedcommercial type, is illustrated and described in,.my prior applicationSer. No. 75,704, filed April 22,- 1936. I A

The said commercial air actuated control mechanism includes anadjustment device, of which the shaft D is the actuating member, whichis employed to vary the magnitude of a reverse, or follow-up",adjustment of the control pressure, following each initial adjustment ofthat pressure resulting from a movement of the pen carriage I, andincludes an adjusting device, of which the member E is the actuatingmember, which is employed to vary the rapidity with which acompensating" adjustment, subsequent and opposite in direction to thefollow-up adjustment of the control pressure, is effected. Furtherreference to the said follow-up and compensating adjustments, and to theabove mentioned potentiometer and air actuated control mechanisms, isplainly unnecessary herein, not only because said adjustments andmechanisms are ,well known to those skilled in the art, but also becausethose adjustments and mechanisms constitute no partof the presentinvention, which may be used with instruments "not including thoseparticular mechsaid doorway, through which a rotatable adjustanisms, andin which the adjusting parts D and E serve very different adjustmentpurposes.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form ofembodiment of my invention nowknown to me, itwill be apparent to those skilled in the art that changesmay be made in the form of the apparatus disclosed without departingfrom the spirit of my invention as set forth in the appended claims andthat in some cases certain features. of my inventionmay be used toadvantage without a corresponding use of other features.

Having now described'my invention, what I claim as new and desire tosecure by Letters Patent is: p

1. An instrument casing formed with a doorway, and. with an aperturethrough which a manually actuatable instrument adjustment device withinthe casing may be actuated, and a member mounted on said casing formovement into and out of a normal position in which it preventsactuation of said adjustment device through said aperture, and a doornormally closing said doorway but movable to open the latter, and whichwhen in its doorway closing position prevents movement of said memberout of the said normal position of the latter.

2. An instrument casing formed at one side with a doorway, and with anaperture through which a manually actuated instrument adjustment devicewithin the casing may be actuated, a door normally closing said doorwaybut movable to open the latter, and a member mounted on said casing forturning'movement into and out p! a position in which it preventsactuation of said adjustment device through said aperture, and a door,said door and member having portions cooperating to hold said memberagainst said turning movement when said door is in position to closesaid doorway.

3. An instrument comprising a casing formed with a doorway and with anapertm'e adjacent ment device extending into said aperture is therebymade accessible for adjustment, a member mounted on said casing formovement into and out of a normal position in which it covers saidaperture and a door normally closing said doorway but movable to openthe latter, and adapted when in its doorway closing position to preventmovement of said member out of its said normal position.

4. An instrument casing formed with a doorway and an aperture throughwhich a manually actuatable instrument adjustment device within thecasing may be actuated, headed pins projecting from the outer side ofsaid casing adjacent saidaperture, and a cover member normally in theposition in which it covers said aperture and formed with slots whichnormally receive said pins and are shaped and arranged to permitmovement of said memb'erout of said position without separation of saidmember from said casing, and permitting other movements of said memberwhereby the latter may be separated from said casing, and a doornormally closing said doorway but movable to open the latter and adaptedwhen in'its doorway closing position to prevent said movements of saidmember.

5. An instrument casing formed at one side with a doorway and anaperture adjacent said doorway and through which a manually actuatableinstrument adjustment device within the casing may be actuated, a memberpivotally connected to said casing for turning movement about an axisinto and out of a normal position in which it covers said aperture, andhaving engaging parts at opposite sides of said axis, and a doornormally closing said doorway but movable to open the latter, andadapted when in its closed position, to be engaged by said engagingparts and thereby prevent movement of said member out of said normalposition.

ANKER E. KROGH.

